Flux bridge transformer



Aprila, 1951 C, C, ROE A 2,547,783

FLUX BRIDGE TRANSFORMER Filed sept. 17, 1948 AGENT Patented Apr. 3, 1951 RIDGLE; TRANSFQRMER.

Charles C. Roe,yLong vieW, Tex., assignrtoR/. G. IjeTourneau, Inc., fStoclrton, Calif., a` corpora,

tion of California `Allliation,Sell.telllher17, 1948, .Serial 1519-,.42t13-8 sgolainis. (01471-242) l; The present invention relates. toand. itY is an object to provide a. novel transformer for sup,-

plying three phase transformed current atfav predetermined value.`

Another object of the invention isY to provide a 3,-phase transformer which employsj a bridge between theprimary. and secondary coils thereof for. the purpose of by-passingAAV excess. flux and preventing the secondary circuitfrom becomingJ overloaded.

Itis, also an object to provide a `means of manual adjustment for this transformer in order to selectively varythev amount o f current to be permitted in, the secondary circuit.

VIt is an additional object to provide a. trans,- former which may be used with an A. C. supply source which has a variable potentialand cycle frequency, but which transformer will maintain asteady output ofitssecqndarvceil- A, further Objectis t0 prei/idea transformer. 0.f the above Characteristicswhichfrwill be Simplein construction, easy to adjust, andveconomicallta build.

These, Objects are aQaQmplis-heds .by means of such structure and relative arrangement of parts as will fully appear by a perusal of the following specification and claims.

Referring to the accompanying drawing:

Figure 1 is a plan view of a transformer embodying my invention.

Figure 2 is a side elevation of this transformer showing the bridge inserted to its maximum depth.

Figure 3 is a flux diagram showing the path of flux during operation.

Referring now more particularly to the characters of reference on the drawings, the transformer shown consists of a three-legged core of stacked laminations I supported by and between mounting brackets 2 and clamping bars 3. The clamping bars are tightened and compress the laminations and hold them in position by bolts 4. On each leg of the transformer core a primary coil 5 is placed, and spaced therefrom on each leg a secondary coil 6 is also placed. This arrangement provides an air space 1 separating the primary and secondary coils. On one side of the transformer a laminated iron bridge 8, which will be referred to hereafter as a flux-bridge, is inserted into space 1. This flux-bridge is suspended from and supported by a triangular mounting pad 9 which is fastened to clamping bar 3 by means of two capscrews I4. Underneath bridge 8 and between it and core I, a shim or 2 shims I0' of a non-magnetic material-suoli as Micartasplad- It will' be seen from lthis arrangement, `that the bridgey is secured; in its-I positionbythevcap-Y screws lv'4fand thehshims I il, andthis'position-maybe regulatedv by loosening'v the capscrews, insert-V..

ingA more s hims and then tightening` the-'capl screws` untilY the bridge' is in nfirmyengragkemernt` with the s hmsf When thereA is non vcurrent being drawn 'fromj the secondary, this-transformer-performsirr the` saine 'manner as certain conventional trans'- formers, `that is a magneticil-ux travelsaround`V luctancepin the iron coreis greaterjthan theVV re luct'ance ofl the vgap'between the core andj thebridge and the fluxjumps the gap andcornpletesits circuit through theI bridge.V rrIhis method-of by-passing the flux which isin excess of VVthat required to maintain the predetermined currentprevents Aany damaging. overload from reaching; the devicev being* supplied from* the transformer; v`In Figure 3, it will'beseenthat the iuxlcreated1 in the iron core l continues to be maintained at full strength in the core (as at l2) until the reluctance in the core (due to current in the secondary circuit) becomes so great that a portion of the flux will jump the gap and travel through the bridge since the path I3 oers a lesser reluctance.

From the foregoing description, it will be seen that there has been produced such a 3-phase flux-bridge transformer as substantially fulfills the objects of the invention as set forth herein.

While this specification sets forth in detail the present and preferred construction of this transformer, still in practice such deviations from such detail may be resorted to as do not form a departure from the spirit of the invention as described in the appended claims.

Having thus described the invention, the following is claimed as new and useful and upon which Letters Patent are desired:

1. A three-phase transformer having a threelegged core containing primary and secondary windings on each leg thereof, said core forming a closed ux path, there being an air space between the two windings on each leg and a bridge of laminated magnetic material inserted in the air space in a manner to overlie each leg of the core which forms a direct flux path between corresponding primary and secondary windings, and

3 insulating shims between said core legs and the bridge, the total thickness of said shims being readily adjustable.

2. A three-phase transformer having a threelegged core containing primary and secondary windings on each leg thereof, said coreforming a closed flux path, there being an air space between the two windings on each leg and a bridge composed of laminations of magnetic material inserted in the air space in a manner to overlie each leg of the core which forms a direct flux path between corresponding primary and secondary windings, and insulating shims between said core legs and the bridge, the total thickness of said shims being readily adjustable, said shims acting as an added reluctance to prevent the passage of flux through the bridge until such time as the reluctance in that portion of the core under the secondary windings becomes greater than the reluctance of the path composed of the shims and the bridge. l

3. A three-phase transformer having a threelegged core containing primary and secondary windings on each leg thereof, there being an air space between these two windings on each leg, a bridge inserted in the air space and overlying each of the legs of the core and being insulated therefrom; said core supported by a mounting structure, a pad overlying opposite sides of said mounting structure, said bridge secured in position by being suspended from said pad, said pad being removably attached to said mounting structure.

. 4. A three-phase transformer comprising a three-legged magnetic material core containing primary and secondary windings on each leg thereof, an air space separating the two windings on each leg, and a bridge of magnetic material inserted in the air space and overlying each of the legs of the core and being insulated therefrom; said bridge being capable of bypassing a portion of the ux in the core when the reluctance of that portion of the core containing the secondary windings reaches a, predetermined value; said core supported by a mounting structure, a pad overlying opposite sides of said mounting structure, said bridge secured in position by being suspended from said pad, said pad being removably attached to said mounting structure.

5. A three-phase transformer having a threelegged core containing primary and secondary windings on each leg thereof, said core forming a closed iiux path, there being an air space between the two windings on each leg and a bridge inserted in the air space in a manner to overlie each leg of the core which forms a direct flux path between corresponding primary and secondary windings, and insulating shims approximately the same length as the bridge between said core legs and the bridge, the total thickness of said shims being readily adjustable, said shims acting as an added reluctance to prevent the passage of flux through the bridge until such time as the reluctance in that portion of the core under the secondary windings becomes greater than the reluctance of the path composed of the shims and the bridge; said core supported by a mounting structure, a pad overlying opposite sides of said mounting structure, said bridge positioned with its laminations perpendicular to said pad andsaid core and suspended from said pad, said pad being removably attached to said mounting structure by capscrews, said capscrews upon tightening causing the bridge to be in firm engagement with said shims.

CHARLES C. ROE.

REFERENCES CITED The following references are of record in the le of this patent:

UNITED STATES PATENTS Number Name Date '771,238 Frank Oct. 4, 1904 1,635,064 Wagner July 5, 1927 2,032,705 Klinkhamer Mar. 3, 1936 2,137,433 Wirz Nov. 22, 1938 2,382,638 Keiser Aug. 14, 1945 2,445,088 Schilling July 13, 1948 

